Steam generator provided with exchangers in series



Dec. 13, 1960 G. ROSS] 2,964,025

STEAM GENERATOR PROVIDED WITH EXCHANGERS IN SERIES Filed July 1, 1955 INVENTOR: GIOVANN\ ROSS //5 A TTORIVEX perature is lower than that of the boiler; the operations United States Patent STEAM GENERATOR PROVIDED 'wrrH EXCHANGERS IN SERIES Giovanni Rossi, Via Gonzaga 7, Milan, Italy Filed July 1, 1955, Ser. No. 519,501

Claims priority, application Italy July 3, 1954 1 Claim. (Cl. 122-421) The present invention relates to a steam generator provided with exchangers in series.

Heat exchangers are known, intended to work as economizers for the steam boiler and, in some circumstances, as vaporizing elements, and are usually provided with automatic devices or with cut-0E valves which operate in response to the variation of fiow conditions within their hydraulic connection. Such evaporating economizers are generally fed, especially small and medium size installations, only during limited periods, and are, therefore, subjected to continuous thermal changes and efficiency changes, passing from a maximum when the generator feed water runs through them at a low temperature to a minimum when the water does not run through them any more and the gases heat the water contained in them, generating steam which is delivered to the boiler.

An object of the present invention is to provide heat exchangers operating partly as economizers and partly as vaporizing elements, automatically transforming themselves into one or the other type according to the thermal level of the water traversing them, without necessity for any valves or automatic control means.

An apparatus in accordance with the invention comprises a plurality of heat exchanger elements traversed in series by the feed water of the generator in countercurrent fiow with the gases coming from the generator itself, the upper portion of each of these heat exchanger elements being hydraulically and unobstructedly connected with the steam zone of the boiler at a point higher than the highest point of the exchanger, so that the exchanger elements will operate as vaporizing elements when the temperature of the water circulating in them corresponds to the temperature of the water circulating in the boiler, and as preheaters when the water temof the various exchanger elements takes place in an automatic and variable manner according to the temperature of the liquid circulating in the exchangers.

The single figure of the drawing is a schematic perspective view which shows a generator provided with four heat exchangers according to the invention.

In the said figure the steam generator is indicated by A (but partly illustrated) and is provided in a known way with a steam collector-separator structure, constituted by the upper receiver 1.

The four heat exchanger elements or exchanger B B B and B are constituted each by a plurality of vertical or upright tubes 2 leading to two horizontal collector tubes, namely the upper and lower collector tubes, respectively 3 and 4. The four exchangers are traveled in series by the feed water of the boiler in a direction opposite to that of the direction y of the hot gases. The water enters first through the inlet 4 into the lower collector tube 4 of the exchanger B and rises in the tubes 2 into an upper collector 3; it then passes from the upper collector tube 3 to the exchanger member 8;; through an upper hori- 2,964,025 Patented Dec. 13, 1960 zontal connecting tube 5 into the upper collector 3 of the next heat exchanger B The water then descends in the tubes 2 of the ex changer B into the lower collector tube 4 thereof and passes from the latter, through a lower connecting tube 6, into the lower collector tube 4 of the next exchanger member B The water there ascends in the tubes 2 of the exchanger B into the upper collector 3 thereof and passes through an upper connecting tube 7 into the upper collector 3 of the last exchanger 3;. The water descends in the tubes 2 of the exchanger B into the lower collector 4 thereof, and then passes through the tube 8 to the steam boiler A. The described path of the feed water is indicated by arrows on the tubes. The upper collector 3 of each exchanger member is hydraulically connected with the receiver 1 of the generator A, in the upper zone (the steam zone) of the receiver itself by means of the ascending tubes or risers 9 leading "to the tube 10 opening into the receiver 1. The lower collector tube 4 of each exchanger is connected to the zone of the liquid of the boiler A at a point higher than the highest point of any of the exchangers, through the risers 11, opening into the tube 12 reaching, in the example illustrated, the lower part of the main receiver 1 (below the liquid level X).

The gases coming out of the steam generator run through the heat exchangers in the direction according to the arrows y, namely in countercurrent flow with the feed water, so that the latters temperature increases as it passes from the exchanger members 13., to the exchanger B So long as the water in the exchangers remains at a lower temperature than the water in the boiler A it is evident that the hydraulic connections in the receiver 1 remain ineffective on account of the impossibility for the water to ascend along the ascending tubes 9 and descending tubes 11 given the greater density of the water circulating in the exchanger with respect to the water circulating in the hydraulic connections with the generator. In such a case the exchanger member operates as a preheater or economizer. Should, however, the feed water reach the temperature of the water in the boiler there will take place, owing to the hydraulic connection with the receiver 1, the automatic operation of the exchanger members as Vaporizers.

It is clear that the changeover from operating as an economizer to becoming a vaporizing element of the exchanger (and vice-versa) comes about in an automatic manner according to the variation of the thermal characteristics of the assembly, just as if ideal valves were operated which opened and closed the hydraulic connections of the exchanger members with the receiver 1. Upon a decrease in the temperature of the feed water, the exchanger members from B, progressively up to B will tend to transform themselves into economizers, whereas, should the feed water temperature increase, the exchanger members will in turn transform themselves from economizers into vaporizing elements, progressively from the exchanger B to the exchanger B In practice the particulars of execution of the generator and exchangers may also vary without for this reason departing from the scope of the invention.

I claim:

In a steam generator having a collector-separator structure defining a chamber including an upper steam receiving portion above a lower water holding portion, in combination, a plurality of heat exchanger members unobstructedly interconnected in series, the upper part of each member being hydraulically and unobstructedly connected in parallel to the steam receiving portion of said chamber and the lower part of each member being hydraulically and unobstructedly connected in parallel to the .water holding portion of said chamber at a point higher than the highest point of any member, each of said heat exchanger members being formed of a plurality of upright tubes; an upper'horizontal collector tube interconnecting as a common connection the tops of each of said upright tubes, a lower horizontal collector tube interconnecting as a common connection the bottom of each of said upright tubes, an upper horizontal connecting tube disposed between adjacent pairs of heat exchanger members and interconnecting the "upper horizontal collector tube of one exchanger member with that of one of an adjacent pair of heat exchanger members, a lower connecting tube disposed between adjacent pairs of heat exchanger members for interconnecting the lower horizontal collector tube of one heat exchanger member with a lower horizontal collector tube of a heat exchanger member of an adjacent pair, an ascending tube leading from the upper horizontal collector tube of each exchanger member and each upper horizontal connecting tube to the steam receiving portion 20 of said chamber, a descending tube leading from the lower horizontal collector tube of each exchanger member and the lower horizontal connecting tube to the water holding portion of said chamber, said heat exchanger members operating as vaporizers when the temperature of water in said heat exchanger member corresponds to the temperature of .water being heated for steam in the generator and said members operating as preheaters when the temperature of water circulating in said members is lower than the said water temperature in said generator.

References Cited in the file of this patent UNITED STATES PATENTS 581,518 Roney et a1. Apr. 27, 1897 1,107,313 Klumph et al. Aug. 18, 1914 1,748,574 La Mont Feb. 25, 1930 1,818,7559 Trainer et a1. Aug. 11, 1931 FOREIGN PATENTS 388,861 Germany Jan. 22, 1924 

